Process of making tetra-alkyl lead



45 cedure may serve Patented Mar. 6, 1928.

umrao STATES KENNETH r. MONROE,

mmouns a couranr, or

warm.

F PENNS GROVE, NEW JERSEY, ASSIGNOR. TO E. I. 1) PORT DE WILMINGTON, DELAWARE, CORPORATE O1 DELA- PROCESS OF MAKING .l!1i'J.IBiAfALKYIl'a LEAD.

No Drawing.

This invention relates to the production of a tetra-alkyl lead, and comprises, as a new process, loy with an alkyl chloride and a neutral 5 hydroxylic compound (preferably functioning catalytically) which is soluble in said chloride, and preferably in the resence of another catalyst and of an inert iluent.

As I have pointed out in my U. S Patent 1,645,389, dated October 23, 1927, the synthesis of lead-alkyls from leadso dium alloy and an alkyl bromide is promoted by the ad diti'o'n of water either per se or in a diluted state. I have now discovered that the syn thesis of lead-alkyls from lead sodium alloy and an alkyl' chloride resembles the bromide synthesis in this respect, despite the lesser chemical reactivity of the chloride, and have made the additional discover that the water may be replaced, either who y or in part, by

another neutral'hydroxylic compound, such' Y ethyl or propyl alcohol.

These hydroxylic compounds (water, al-.

cohol, etc.) have a great influence on the course of the reaction, being in fact essential from a practical manufacturing standpoint.

If highly purified alkyl chloride (or bromide) is l lnermitted to react with pure lead sodium 11 oy the yield of lead alkyl is negligible under the same conditions which re- Sult in a substantialyield when alkyl chloride (or bromide) containing an appreciable amount (for example 0.4% based on the weight of a l halide) of. water or an alcofl hol is used. On the'other hand the presence of anexcessive initial amount (for example 4.0%) of water or an alcohol causes excessive side-reaction (for example, the evolu-, tion of hydrogen) and. causes a diminution in yield from that obtained when an optimum amount is present. Theaddition 0 alcohol orwater may be made entirely in the beginning, or in portions from time to time as thereaction proceeds. This latter proas a mode of control for obtaining a smooth reaction, particularly when thereaction is carried out on a large scale andv is, therefore, more liable to so 5 den and disastrous temperature surges. It

. has also been found desirable to assist in the control of the reaction on thelarger scale by p dilution of the liquid reaction mass with an inert miscible liquid; such liqmd may be,

for example, benzene or other mer t hydro- 1 1 Application filed mar 25; 1924. s mi No. 701,641.

the interaction ofa lead-sodium al- O.'4% alcohol and water. 5 cc. additions. ethyl alcohol were then added. The tube steam distillation. 2 cc.

and maintained at carbon which is miscible with" the alkyl chlor de'used.

The invention may be illustrated by thefollowmg examples:

(1) 106 grams very pure lead-sodium alloy contalmng 14.6% sodium (the compositlon of the alloy being expressible as a mixture of 44v parts of PbNa with 56 parts of P bNa was placed in a steel tube with 60 cc. hlghly purified ethyl chloride. The tube was closed and placed in an oil bath where 1t was rotated while the temperature was gradually raised to C. and maintained at 80 U. for eight hours. The tube was then removed, cooled, opened and the contents thoroughly extracted with dry, alcohol-free ether. On filtration and evaporatron of the other only a vanishingly small yield cc.) of lead tetra-ethyl was ob-. tamed.

(2) 106 rams very pure lead-sodium al loy contalnmg 14.6% sodium was laced in a steel tube with 60 cc. highly pur' ed ethylchloride to which 1 cc. absolute ethyl alcohol had been added. The. tube was then closed and placed in an oil bath where itwas rotated while the temperature was raised gradually to 80 C. and maintained at 80 C. for eight hours. The tube was then i'emoved, cooled, opened, and the contents thoroughly extracted withdry, alcohol-free ether. On fil ration and evaporation of the ether 15 cc. lead tetra-ethylwere obtained. V (3) 100 grams lead-sodium alloy contain mg 14.6% sodium were placed 111- 8. steel tube with 130 cc. ethyl chloride containin was close placed in an oil bath, and-ro- I 'tat ed while the tem erature was 'gradua y f raised to 65 C. an -ma intained at 65 C. for 48 hours. The tube was then openedand the excess ethyl chloride and lead tetra-. ethyl separated from the residual lead by lead tetra-ethyl were obtained. I

(4) 100 grams lead-sodium alloy contain ing.14.6% sodium were placed in a steel tube with 00c; ethyl chloride containing'0.4% alcohol" and water. The tube was closed,

laced in an oil bath, and-rotated while the .106 temperature was gradually raised-to 65 C,

I 0.. or 48 hours. {The tiibe'was-then opened and the excess ethylchloride and lead tetra-ethyl separated from the residual lead by steam distillation. 19 cc. lead tetra-ethyl were obtained.

The reaction us' an ethyl chloride, as will have appeared 111 the above examples, is preferably carried out at a temperature above 60 C. as compared with the temperature of 2530 C. which gave best results with ethyl bromide as described in my said copending application. It is to be understood, however, that my invention is not limited to working at any particular temperature or temperatures.

. lecu ar percentage of a neutral h lea sodium a Instead of water or alcohol per se aid the reaction, I may use, as above indicated, water or alcohol diluted by dissolving therein a salt or hydroxide such as potassium carbonate, potassium hydroxide, sod1um chlcride, or a salt ofa metal whose hydroxide s insoluble or only slight] soluble, such as magnesiumfand calcium 0 lorides.

The hydroxylic compound used seems to act as a true catalyst, being continually regenerated during the progress of the reduction b a secondary reaction between the sodium ydroxide (or alcoholate) and the hydrochlori'c acid formed. This accounts for the effectiveness of the small proportion of hydroxylic compound used. K

ereit is found desirable'to use an additional catalyst, such catalyst is preferably of the type used for the Grignard synthesis, such for example as tertiary amines dimethylaniline, pyridine, etc), esters (et yl acetate), ethers, etc.

I claim! 1. The process of producing a tetra-alkvl lead from a lead alloy and an alkyl chloride, which compri'sestreat' one atomic proportion'of lead, alloyed with two atomic proportions of a monovalent element capable of liberating hydro en from water, with an alkyl chloride in t e presence of less than 5.1 molecular percentage, based upon said' chloride, of a neutral hydroxylic compound soluble in the alkyl chloride.

2. The process of producing a tetra-alkyl lead from a lead alloy and an alkyl chloride, which com rises treating one atomic proportion of lea alloyed with two atomic proportions of .a monovalent element capable of liberating hydrogen from water, with an alkyl. chloride in the presence of from about 0.5 to 1.3 molecular percentage, based upon said chloride, 'of a neutral hydroxylic compound soluble in the alkyl chloride.

e process of roducing a tetra-alkyl lead from alead-sodihm alloy having a sodium "content of about 14.6 percent and an a l chloridewhich comprises ,treatin the lloy with the alkyl chlori e in the. resence of from about 0.5 to 1.3 modroxylio compound, soluble insaid chlori e, to enable the combination.

between the lead and the alkyl chloride to proceed, by the addition of the hydroxylic compound at such a' 7. A process as defined in claim 3 in which A the alkyl of the alkyl chloride contains from 1 to 4 carbon atoms.

8. The process of producing tetra-ethyl lead which comprises inducing a reaction between an alloy of the formula PbNa ethyl chloride, and water in an amount less than 4 percent based upon the weight of the ethyl chloride and recovering the tetraethyl lead forme 9. The process of producing tetra-ethyl lead which comprises'inducin a reaction between an alloy of the formula PbNa, ethyl chloride, and water and amount less than 4 percent based upon the weight of 'the ethyl chloride, and recovering the tetra-ethyl lead formed.

10. The process of producing tetra-ethyl lead which comprises maintaining, at a temperature above 60 0., a mixture containing an alloy of the formula PbNa ethyl chloride, and from about 0.2 to 2 waterbased upon the weight of ethyl chloalcohol in an .0 percent of ride present, until the reaction is about completed.

which a mixture of water and ethyl alcohol is used in place of water.

12. The process of producing tetra-ethyl lead which comprises gradually adding a neutral .hydroxylic compound soluble in ethyl chloride to a mixture containing the lead-sodium allog Pbll'a and ethyl chloride, the amount of ydroxylic compound prescut at any one time inthe reaction mixture bein just sufficient to enable the combination etween the lead and' the eth l chloride to proceed, by the addition of the liydroxylic compound at such a rate that excessive evolution of free hydrogen is avoided.

The processof producing tetra-ethyl lead which comprises gradually addin water to a mixture containing ethyl c oride and the alloy PbNa the amount of water present at any one time in the reaction mixture being not substantially in excess of that required to enable the combination between the lead and the ethyl chloride to rooeed actively, by the addition of the hy oxylic compound at such a rate that excessive evolution of free hydrogen is avoided 14. The process of producing tetra-ethyl lead which comprises gradually ad water to a mixture containing ethyl c oride and the alloy PbNa,, the amount of water present at any one time in the reaction mix- -ceed actively, by the addition of the hydroxylic compound at such a rate that excessive evolution of vfree hydrogen is avoided, and maintaining the reaction mixture at a temperature above 60 (3., throughout the major part of the reaction period.

15. The process of producing tetra-ethyl lead which comprises gradually adding water and ethyl alcohol to a mixture containing ethyl chloride and the alloy PbNa the amount of water and alcohol added amounting to between 0.2 and 1 percent, based upon the weight of ethyl chloride present.

16. A process as set forth in claim 13in which ethyl alcohol replaces at least a substantial part of the water which is added to the mixture of ethyl chloride and lead-so- 'dium alloy.

17. Process of making an alkyl compound of a metal of the second sub-group .of the fourth periodic group, comprising alloying the metal with a highly electro-positive metal, and treating the alloy under reaction conditions with an alkylating agent in the presence of a hydrocarbon liquid.

18. The process of making a lead ethyl which comprises reacting a lead-sodium-alloy with an ethylating agent in the presence of a hydrocarbon liquid.

19. The process of claim 18 in which the hydrocarbon liquid is a lower hydrocarbon of the benzene series.

In testimony whereof affix my signature.

KENNETH P. MONROE. 

